Thermally evaporated Bi2Te2.45Se0.55 thin films were examined for structural alterations and electrical conductivity. Crystallite size, micro-strain, and dislocations were all calculated using the XRD data. By using transmission electron microscopy, the morphology of thin films was investigated (TEM). The study was performed within a temperature range of (300 – 500) K. The electrical energy gap and the conductivity of the as-deposited and annealed (373, 473K) Bi2Te2.45Se0.55 films were measured. The obtained values are (0.27, 0.26, 0.24 eV) and 3.6×103, 3.7×103 and 4.1×103 ohm-1.cm-1 respectively. Hall coefficient, the mean free time, the diffusion coefficient of holes, and the diffusion length, charge carrier's concentration, charge carriers' scattering mechanism, and Hall mobility were also examined. The obtained values of the charge carrier's concentration are 2.12×1017 -2.73×1017 cm-3. The direct and indirect allowed energy gap decreased with increasing annealing temperature. The obtained values of indirect band gap and direct band gap ranges from 0.27- 0.24 eV and 0.375- 0.379 eV, respectively.
Structural and optic consistent of the amorphous system of concentrations (65-x)B2O3-xSb2O3-10 ZnO-25 Na2O (x = 0, 5, 10, 15, 20 mol%) were carried out using X-ray diffraction (XRD) examination, optical absorption spectrum (Ultra-violet) spectrophotometers UV and Fourier-transform infrared spectroscopy (FTIR) analysis. XRD pattern revealed the non-crystalline nature of investigated samples at different concentrations. Also, the optical band gap was evaluated at different concentrations. Results revealed that band gap values increase by increasing antimony concentration from (3.1–3.45) eV. From optical measurement spectra, Urbach energy ΔE evaluated at different concentrations. The structural unit of BO4 transformed to BO3 due to the change of the molar volume, density. The increase of density of any glassy system means that the average interatomic distance is reduced. This leads to the increase of the force constant leading to the blue shift of IR bands and the band edge, and N4 fraction with antimony oxides concentrations which leading to closing up of amorphous structure.
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